hydrogen peroxide

noun

: an unstable compound H2O2 used especially as an oxidizing and bleaching agent, an antiseptic, and a propellant

Examples of hydrogen peroxide in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
If the stain remains, apply hydrogen peroxide, and let stand. — Madeline Buiano, Martha Stewart, 25 June 2026 Workers were seen in recent days pouring hydrogen peroxide into the pool in an attempt to kill the algae. — Matthew Daly, Fortune, 24 June 2026 The chemical compound can slowly break down when exposed to hydrogen peroxide, which in turn would create oxygen. — Mack Degeurin, Popular Science, 1 July 2026 Household items like vinegar or hydrogen peroxide can deeply sanitize cutting boards. — Mary Marlowe Leverette, The Spruce, 28 June 2026 See All Example Sentences for hydrogen peroxide

Word History

First Known Use

1872, in the meaning defined above

Time Traveler
The first known use of hydrogen peroxide was in 1872

Rhymes for hydrogen peroxide

See All Rhymes for hydrogen peroxide

Browse Nearby Words

hydrogen oxide
hydrogen peroxide
hydrogen selenide
See all Nearby Words

Cite this Entry

“Hydrogen peroxide.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hydrogen%20peroxide. Accessed 7 Jul. 2026.

Copy Citation

Kids Definition

hydrogen peroxide

noun
: an unstable liquid compound containing hydrogen and oxygen and used especially for bleaching and as an antiseptic

Medical Definition

hydrogen peroxide

noun
: an unstable compound H2O2 used especially as an oxidizing and bleaching agent and as an antiseptic

More from Merriam-Webster on hydrogen peroxide

Nglish: Translation of hydrogen peroxide for Spanish Speakers

Britannica.com: Encyclopedia article about hydrogen peroxide

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)
See More

Popular in Wordplay

See More

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

Is that lie 'bald-faced' or 'bold-faced'?

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
hangman letters and game
Hangman Lightning Round Figure out which word fits in the blanks.
See All